Electrical power may be transmitted from a generation source to consumers via overhead conductors strung between towers or poles. Electrical power is conventionally transmitted in phases wherein multiple conductors are utilized. One or more of these conductors may be a "hot" conductor that carries a specified amount of alternating current electric power. Flashover may result if contact is made between two hot conductors or between a hot conductor and ground. Non-grounded contact with a hot conductor, such as when a bird sits upon a hot conductor, typically does not result in flashover.
The transmission of electrical power from a generation source to residential areas typically involves a combination of transmission devices which make up a transmission system. In a typical transmission system, power is generated by a power plant such as a hydroelectric installation, a steam installation or a nuclear plant. The output from a power plant generator is normally about 25 kilovolts (kv). The output from a power plant generator is typically transmitted to a step-up substation where the voltage is increased to a transmission line voltage of 230 kv or higher. The next substation encountered is typically a transmission substation where the transmission voltage is decreased from the transmission line voltage to a sub-transmission voltage of approximately 69 kv. A distribution substation is then typically used to step the voltage down from the transmission voltage to a distribution voltage of about 5 to 35 kv. The distribution voltage is the voltage that is transmitted to a residential area, either through overhead or underground distribution systems. Single phase transformers are typically provided at the residential level to reduce voltage to a 240-120 volt, single phase, three wire residential power entrance.
Because uninsulated conductors are typically less expensive than insulated conductors, many electric power suppliers utilize uninsulated conductors for the transmission and distribution of electric power. Although uninsulated conductors may be less expensive to install than insulated conductors, potentially costly problems may arise from the use of uninsulated conductors. Adequate clearances between conductors and/or other grounded objects may not be sustainable during adverse weather conditions (i.e., storms and high winds). As a result, the potential for flashover caused by uninsulated conductors contacting each other or other objects may be increased. Another source of flashover may be caused by large birds and animals which have sufficient size to make contact with a hot conductor and a grounded object or another conductor. In addition, falling trees and tree branches may cause contact between hot conductors and ground which may result in flashover.
Substations typically include various steel structures for supporting power transmission and distribution equipment, such as circuit breakers, transformers, capacitors, regulators, hook switches and the like. Uninsulated conductors typically extend between the equipment in a substation in various directions and configurations. Because workers often work in close proximity to the equipment in a substation, it is typically desirable to cover at least some portions of the uninsulated conductors as well as grounded structures in the vicinity of uninsulated conductors.
Flashover may result in power outages which are undesirable to electric power suppliers and to consumers. For existing power transmission and distribution systems, electric power suppliers may find it desirable to replace uninsulated conductors with insulated ones in order to reduce the likelihood of flashover. Unfortunately, the cost of replacing uninsulated conductors with insulated conductors may be expensive. Furthermore, an interruption in the delivery of power may be required to replace uninsulated conductors. This may be economically disadvantageous to an electric power supplier as well as being undesirable to electric power consumers.
Insulating covers for protecting workers from hot, uninsulated conductors, as well as for protecting against flashover, are available. These covers conventionally include thick rubber tubing, heat-shrinkable tape, and wrap-around covers. Unfortunately, there are drawbacks associated with installation methods for each of these types of covers. Thick rubber tubing can be somewhat bulky and difficult to install. Furthermore, tubing covers may require that a conductor be disconnected from service so that the conductor can be inserted through the tubing. Such electrical power service interruptions may be economically disadvantageous to an electric power supplier as well as being undesirable to electric power consumers.
The use of heat-shrinkable tape typically requires the use of a torch or other heat source for shrinking the tape to a conductor. The use of a torch or other heat source, particularly around substation equipment, is generally undesirable and can be labor intensive. Wrap-around covers typically do not snap together and typically are secured to a conductor or other structure using ties. Unfortunately, this method can be a somewhat labor intensive process as well.
Insulating covers are available that do not require that a conductor be removed from service. These covers are typically flexible panels having elongated opposite edge portions that are configured to be joined together to enclose a conductor or other elongated structure. Unfortunately, operations for joining the edges together on these types of covers can be labor intensive.